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Just posting a pure technical question

There are two major technical obstacles with electric cars. first, energy density. Tesla has resolved this problem, if not fully, by outstanding engineering and also thanks to the advance in battery technology.

Second, battery uniformity. No manufacture can guarantee the batteries are uniform when produced. This means, each of the thousands batteries hosted in Model S body will behave differently in daily usage. This situation will worsen as time goes on. this might also cause some safety issues in the long run, since un-uniform batteries will heat up pretty quickly and thus might explode. I know Tesla has some patents in battery controlling system, which is supposed to alleviate the problem. I'd be most appreciated if I can have some details on this.

Exploding batteries will be VERY rare. The entire manufacturing process is outsourced to Panasonic which makes the entire cell. It is up to them to maintain tollerences and failure rates within specifications. Based on the "hopla" surrounding this new car, I suspect Tesla has set the acceptable failure rate VERY VERY low.....ie 1/100,000 or lower and based no the 10s of thousands od dollars these batteries costs each, that is not too much to ask for.

Based on that, it is not exploding batteries that Telsa is worried about, or even uniformatiy for that matter. It is long term usage and "high" use periods. For an EV , nothing is worse than long periods of extended use like going 120kph down a highway for 3hrs with no stopping. The only way that could be more abusive is if a chunk of that trip was uphill. You can add another scenario to "high" usage that is bad for the batteries and that is drag racing. Testing out the 5.6sec 0-60mph about 100x a day would heat them up real good too.

There are probably 20 different ways to cool a battery, with air and liguid being the most used as well temperature detecting forced shutdowns being the 3rd most common. Tesla used a combination of all 3, mostly relying on liquid.

Others will provide more detailed examples of what liquid is used and at what temp the shutdown (or power reduction) kicks in. I just wanted to properly frame what conditions the battery is cooled under.

The.... is it 1,000,000 plus... accumulative miles on the Roadsters has given me faith in Tesla's battery design. I don't see any posts in the Roadster forums about exploding batteries but I do see many posts about racing and other rough battery treatment with no issues.

Uniformity is a big problem of lithium-ion battery. One bad battery in 100 will greatly shorten the life span of the whole package. As per Roadster, Roadster uses a different chemical lithium-ion battery which is much more mature and claims much better uniformity. That is what I am worrying about. Also, driving down on highway at 120km/hour until the battery runs out is much anticipated, Tesla should have attended to that though.

According to Tesla, one bad apple doesn't spoil the whole batch. They are isolated to prevent this problem. This is part of their secret formula.

blackscraper:
You can find what Tesla did for the battery here: http://www.teslamotors.com/blog/most-coddled-automotive-battery-ever
- Alfred
http://web.me.com/alfredar

Thanks All for the information, special thanks to Alfred. That really alleviate my concern

I ride a Bike-E recumbent bicycle with an Ecospeed motor kit. It has a LiFePo 10 AH nominal 36v battery pack. Each cell is connected separately to the controller which monitors cell condition and "balances" output. There are only 12 cells so this is not so complicated. I don't know how Tesla will do it with thousands of cells but I suspect that something like this is the basic approach.

I believe the batteries are considerably safer than gasoline. There have been some impressive wrecks with a Tesla, one with an SUV that ended up sitting on the battery pack. The car was totaled but the driver walked away and there was no issue with the battery.

I have been working with batteries on electric vehicles for 5 years now and have never experienced anything close to an exploding battery. I have seen a controller explode (not on a Tesla) but the batteries are quite stable, especially when compared to gasoline.

http://www.wreckedexotics.com/tesla/tesla_20091020_001.shtml

The only obstacle these days is price. Batteries are light enough
and small enough and can be recharged fast enough to compete against any other propulsive technology.

Ramon123 said:

"The only obstacle these days is price. Batteries are light enough and small enough and can be recharged fast enough to compete against any other propulsive technology."

*** End quote. ***

Although technologically there are batteries that can be charged in 5 or 10 minutes, the infrastructure does not yet exist to supply high enough power on a commercial basis to fully charge a 300-mile car, or even a 100-mile car in anything like the time a gasoline car can be fueled.

This, along with the cost of batteries, is a real obstacle to the widespread adoption of EVs.

Like most new technologies, adoption will be gradual, as a few people are willing to accept the costs and limitations, and infrastructure is installed slowly at first, and the two (adoption and infrastructure) grow together.

By developing a battery pack that is much safer than gasoline, Tesla has made a significant contribution. And by putting it in a car that most owners do not buy primarily for long-distance travel, but which is capable of 245 miles of range, Tesla has side-stepped, to some extent, the infrastructure deficiency. For me personally, the Roadster is too small for long road trips, and I would not want to leave it in the places I generally park when I do take road trips, so the scarcity of public charging is not an impediment. It was in my view, a wise decision.

But fast-charging infrastructure is still an obstacle to be overcome if America is to go electric. Nissan claims that their L3 charging stations can charge a Leaf to 80% in half an hour. With a real range of around 85 miles, 80% is 68 miles. Round that to 70, and to fully charge a Roadster, with its 245 mile range, would take an hour and three-quarters. I.e., every 3:45 of driving you have to stop and charge for 1:45. Most people will not accept that while gasoline remains affordable. To get a 10-minute charge time for a 50 kWh pack you'd need to deliver 300 kW. Double that for a 5-minute charge. You're either delivering so much current that the cable and connector would be hard to lift, or working with voltage so high as to be extremely dangerous. These are not trivial issues and will take time to address. I believe we can and will address these issues, but we may have to change our entire outlook regarding personal transportation. And it might not be able to happen until gasoline becomes too expensive for ordinary folks.

The EVs of today, with all their limitations, are demonstrating that electric transportation is possible. But fueling a gasoline car is going to remain much faster than charging an EV for a very long time.

The Leaf aren't utilizing the full potential of the fast chargers. What is the battery voltage for the Roadster, 375V ? At 125A charging current that is 46.9kW. The usable part of the Roadster battery is 53kWh, 80% of that is 42.4kW. (42.4/46.9)*60=54 minutes to charge the Roadster from 0 til 80%.

That is a charging speed of (245*0.8)/0.9=218mph. Not too bad ?

The Model S with a 480V pack voltage would get 60kW from the fast chargers, or ~1 hour to charge the pack from 15% to 80%. Perfectly adequate for me at least.

Some details on the technology used in the current generation (speculative, might have changed since):

News:
http://sacarfan.co.za/tag/long-heat-exchanger/

tech info from provider:
http://www.dana.com/wps/wcm/connect/9b2efd80420c42539b19db14c3bad2bf/dex...

This might also be of interest to some :

a master thesis on the thermal management of battery systems.

http://ir.library.dc-uoit.ca/dspace/bitstream/10155/111/1/Ramotar_Lokend...

".... Round that to 70, and to fully charge a Roadster, with its 245 mile range, would take an hour and three-quarters. I.e., every 3:45 of driving you have to stop and charge for 1:45. Most people will not accept that while gasoline remains affordable...."

Actually, that sounds pretty close to reasonable for people who drive safely.

If the charging is at restaurants and hotels, four hours driving / an hour to recharge is something most people will do, because most people stop to eat already.

That said, the fast charge infrastructure certainly isn't here yet, although there seem to be no *technical* barriers. Level 3 charging stations need to be placed at strategic points surrounded by hotels and restaurants, in order for long road trips to work.

If you are worried about exploding batteries, just think, people hold them up to their faces billions of times a day. Haven't heard about anyone's ear getting blown off from their phone.

It's always amusing to see the catastrophes people will dream up when it comes to a new technology they are unfamiliar with. Imagine if EV's had dominated the last century and someone recently invented the ICE. People would say "You want to strap a giant tank of highly flammable liquid to a car? Are you insane?"

I've read that 35 ICE cars go up in flames each and every day in the USA. It's reasonable to ask about battery safety, but what Tesla has done for the Roadster's battery pack makes it WAY safer than any gas tank.

It's about 33 car fires per hour in US :

· According to the National Fire Protection Association (NFPA), one out of five reported fires is a car fire. In fact, 18 percent of all fires takes place on a highway or other road and involves a motor vehicle.

· Also according to the NFPA, 33 car fires are reported every hour across the country, with one person per day dying in a car fire accident in the years between 2002 and 2005.

· According to the National Fire Protection Association, there were 258,000 vehicle fires in 2007 and 385 deaths. There were 1,675 injuries.

· According to the National Fire Incident Reporting System (NFIRS), teen with drivers' licenses and young adults are the demographic most likely to be involved in a car fire accident. Young males were more likely to be a victim of a car fire than young females.

· There is a vehicle fire every 96 seconds in the United States.

· The majority (75%) of highway vehicle fires are caused by mechanical failures or other car malfunctions. However, vehicle fires caused by collisions are responsible for almost 60% of vehicle fire deaths.

· One out of three vehicle fire injuries occur when car fire victims attempt to fight the vehicle fire without the help of emergency workers and experienced firemen.

· In 2007, vehicle fires cost Americans $1.41 billion dollars.

source:
http://www.chandlerlawgroup.com/library/national-vehicle-fire-statistics...

The Leaf aren't utilizing the full potential of the fast chargers. What is the battery voltage for the Roadster, 375V ? At 125A charging current that is 46.9kW. The usable part of the Roadster battery is 53kWh, 80% of that is 42.4kW. (42.4/46.9)*60=54 minutes to charge the Roadster from 0 til 80%.

That is a charging speed of (245*0.8)/0.9=218mph. Not too bad ?

The Model S with a 480V pack voltage would get 60kW from the fast chargers, or ~1 hour to charge the pack from 15% to 80%. Perfectly adequate for me at least.

Except that the roadster, and so far what we know of the model S, doesn't/won't have an insane 480v 125A 2-3 inch thick DC connector.

Nice to see that this forum completely ignores quote tags and doesn't have preview or edit options.

*FACEPALM*

I won't buy the Model S if it doesn't support fast charging. I do not think Tesla would be that ignorant, to release a car with a 90kWh battery and no way to fast charge it.

You seem to have missed my point; so called "zap charging" is a myth. It is not something that Tesla lacks, but rather something that doesn't exist. It's a pipe dream that Nissan is pushing to ease people's range anxiety.

@psusi, Go to your nearest Tesla store and check out their HPC. It uses 480v and charges the roadster in under 45 minutes.

The HPC won't do anything for me. First, it's too slow for away from home charging. Second, noone deploys these around Norway.

At home 16A 230V will be fast enough for me.

What is being deployed around Norway is 62.5kW CHAdeMO chargers. These I need to be able to use. 1 hour to fill a 90kWh battery from 15% to 80% is perfect for road trips.

If it has a CHAdeMO plug or a J1772-DC or a proprietary Tesla-DC plug doesn't matter much as long as they're electrically compatible and adapters exists.

@Klaus according to the specs on the web site here, the HPC is 240V and 70A. From what I have read, Telsa got them to increase the J1772 standard to 70A. I have not seen any specs stating that the Tesla can accept more, let alone the ~125A at 480V it would take to charge it that fast, which would also require a cable that is much thicker, heavier, and harder to handle.

Ahh, this CHAdeMO station sounds like it might get somewhere in the vicinity of a 45 minute 70% recharge, assuming that the battery pack is near 500V. Will the S have this, or just the J1772?

That is one big honking plug.

The HPCs at the stores are not the same as the ones for sale on the site.

Battery costs are not, of course, simply a matter of initial
purchase price. Replacement costs are, of course, to a large extent unknown, except that they will surely be less than what we are paying nowadays. This all figures into the calculation of
which battery pack size is best. Generally, the smallest would
seem to be the better economic decision, assuming that a lot of trips beyond the range of the battery pack are not likely. But
since there are so many unknowns here and because battery technology is in such a state of flux, the better choice may very well be to forego any new car purchase, electric or otherwise, and
wait and see. With news floating around of batteries that can
last several decades and be recharged very quickly, I'm in no hurry to go electric. And anyone who thinks by doing so they will have the slightest effect on anything environmental is fooling themselves. One person, or even a million people, will have no discernible effect. We need hundreds of millions of electrics
and that means much cheaper prices. They are coming, it's just a matter of time.

They are coming, it's just a matter of time. (Ramon123)

This is only true if there are a few thousand buyers now and a million buyers a little later. I do not blame you, your point is entirely valid, but you should not overlook that if everybody would use the same rationale, we would be stuck where we are and progress would not be made.

It is true that a million cars converted from ICE to electric do not make a discernible difference on the environment. But to get to the point where it really does make a difference, you need those million early adopters in the first place. (And if there were a million ICEs replaced by EVs in Berlin and its suburbs, walking and cycling the city would be a pleasure for the fresh air alone.)

Also, the "wait for better battery technology" logic is faulty. There will never be a time when better technology is not coming, so there would never be a time to buy.

Are you still using an AT, waiting for the ultimate PC upgrade?

Same argument for waiting to buy a computer. It's a matter of whether you want the features currently available or are going to wait forever for the new features "just around the corner".

"I want it NOW!!!"

Of course, I can't have it yet.


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